Currently, by virtue of low power consumption, low costs, good interworking, and another advantage, a manner in which a vertical cavity surface emitting laser (VCSEL) works with a multimode optical fiber to transmit an optical signal is widely applied to data center interconnect (DCI). However, for an ordinary non-return to zero (NRZ) modulation system, performance of the system quickly degrades with an increase of a signal modulation rate and an increase of an optical fiber transmission length. When a total transmission capacity is unchanged, a single-channel transmission rate may be reduced by increasing a quantity of wavelengths, and therefore in theory, a wavelength division multiplexing (WDM) technology, such as a short-distance wavelength division multiplexing sWDM technology, can effectively improve a transmission capacity of the system.
The sWDM technology may reduce a single-channel transmission rate and a quantity of optical fiber resources. Currently, some manufacturers in the industry use a QSFP28 standard to implement 100-GE transmission, that is, to implement short distance interconnection four-wavelength transmission by using the sWDM technology. The four wavelengths are 855 nm, 883 nm, 915 nm, and 945 nm respectively, and a transmission rate of each channel is 25 Gbps. A transmission system for implementing short distance interconnection four-wavelength transmission may be shown in FIG. 1. FIG. 1 is a schematic structural diagram of a prior-art transmission system used for implementing short distance interconnection four-wavelength transmission. A transmit end bit stream is a binary signal carrying information; a limiting driver is configured to perform amplification and offset addition on the binary signal, to drive a voltage of a corresponding transmitter; the transmitter is configured to convert a received electrical signal into an optical signal; a short wavelength division multiplexer (SWD Mux) is configured to combine optical signals of four wavelengths into one optical fiber link; a wideband OM4 is configured to complete optical signal transmission; a short wavelength division demultiplexer (SWD Demux) is configured to demultiplex the optical signals of four wavelengths into different receivers; the receiver is configured to convert the optical signal into an electrical signal; and symbol determining is used to determine an analog electrical signal as a binary signal. However, spacings between the four wavelengths are relatively small and there is a large quantity of wavelengths. Consequently, there is interference between channels in the optical fiber during optical signal transmission.